Soft nickel modified cobalt based nanomaterials: An advanced approach for green hydrogen generation

Green hydrogen is notably a promising candidate for the sustainable future. Here, we are synthesizing a series of Ni modified CoFe₂O₄ nano-catalysts of composition, Co_1−xNi_xFe₂O₄ (x = 0.00–0.06) by inorganic sol–gel auto-combustion synthesis route for analyzing their physical, optical, magnetic, and electro/photo catalytic water splitting characteristics. XRD examination confirms the spinel cubic phase of prepared compositions, whereas the Rietveld refinement shows the single-phase formation of the developed materials. The spherical and cubic shaped agglomerated grains are observed in the FESEM images of CF1 (x = 0.00) and CF4 (x = 0.06) specimens. With low Ni doping (x = 0.00 to 0.04), there is a decline in the band gap of prepared samples from 2.14 to 1.80 eV, but at high Ni doping (x = 0.06), it increases to 1.99 eV, respectively. Raman and XPS studies confirmed the existence of spinel structure and the proper oxidation states for elements present in the specimens for the nanomaterials. The surface area of the CF1 and CF4 samples are computed from the BET data. As per photocatalytic results, the CF3 catalyst attains the highest photocatalytic hydrogen generation of 30.32 mmol g_cat^-1. Also, with the increasing Ni doping concentration, there is an increase in overpotential at 10 mA/cm³, which shows that the CF3 electrocatalyst have maximum HER electrocatalytic performance. Therefore, with this outstanding catalytic water splitting performance, the nickel doped CoFe₂O₄ are advantageous for the production of clean and renewable hydrogen.